From: Shradha Shah <sshah@solarflare•com>
To: David Miller <davem@davemloft•net>
Cc: <netdev@vger•kernel.org>, <linux-net-drivers@solarflare•com>
Subject: [PATCH net v3 0/2] sfc: Restrict PIO for 64bit arch in order to avoid data corruption
Date: Thu, 29 May 2014 11:18:44 +0100 [thread overview]
Message-ID: <53870984.6020803@solarflare.com> (raw)
This patch series
Fixes: ee45fd92c739("sfc: Use TX PIO for sufficiently small packets")
The linux net driver uses memcpy_toio() in order to copy into
the PIO buffers.
Even on a 64bit machine this causes 32bit accesses to a write-
combined memory region.
There are hardware limitations that mean that only
64bit naturally aligned accesses are safe in all cases. Due to being
write-combined memory region two 32bit accesses may be coalesced to
form a 64bit non 64bit aligned access.
Solution was to open-code the memory copy routines using pointers
and to only enable PIO for x86_64 machines.
This bug fix applies to v3.13 and v3.14 stable branches.
Jon Cooper (2):
sfc: use 64-bit writes for PIO.
sfc: Restrict PIO to 64-bit architectures
drivers/net/ethernet/sfc/io.h | 8 ++++++++
drivers/net/ethernet/sfc/tx.c | 24 +++++++++++++++++++-----
2 files changed, 27 insertions(+), 5 deletions(-)
next reply other threads:[~2014-05-29 10:18 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-05-29 10:18 Shradha Shah [this message]
2014-05-29 10:20 ` [PATCH net v3 1/2] sfc: use 64-bit writes for PIO Shradha Shah
2014-06-02 5:25 ` David Miller
2014-05-29 10:20 ` [PATCH net v3 2/2] sfc: Restrict PIO to 64-bit architectures Shradha Shah
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